The goal of this study is to evaluate the somatic and neurobehavioral development of children (first 3 years) born to methadone-maintained mothers (MM) and compare them to a matched control group. In addition to methadone maintenance, other prenatal and postnatal variables will be examined to determine if any other inter-relationships exist. At present, we are following 42 MM children (21 males, 21 females) and 25 control children (14 males, 11 females). We have had a loss rate of approximately 31% in methadone babies and 25% among control children. Most of our children are over 18 months of age and are seen routinely every 3 months. They are evaluated neurobehaviorally every 6 months. Emergency medical care is also provided. Our preliminary findings have shown the following: 1) the incidence of URI and otitis media are significantly higher in the methadone children after 12 months of age; 2) the incidence of abnormal neurological findings including developmental delays are significantly higher in the methadone children; 4) Bayley mental and motor indices are consistently lower in the methadone children, but only reach significance when methadone males are compared to control males. (There are no significant differences among the female groups.) 5) Delays in speech development in the methadone children have been noted, but the numbers are still too small to warrant data analysis. In order to further confirm these preliminary findings, follow-up care and testing should continue for a longer period.